White-Light Coronal Fine Structure
Session 92 -- Solar Active Regions and Solar Wind
Oral presentation, Wednesday, 11, 1995, 10:00am - 11:30am

[92.04] White-Light Coronal Fine Structure

L. J. November (National Solar Observatory), S. Koutchmy (Institut d'Astrophysique)

White-light coronal observations are reported from the eclipse of July 11 1991 taken with the 3.6 meter Canada-France-Hawaii Telescope on Mauna Kea. The observations provide the highest resolution observations ever achieved because of the unique opportunity of observing the totally eclipsed sun with a large aperture telescope. We study the time series obtained with a 70mm acme photograph camera in a $10\times10$ arcmin field of view just above the solar limb. Spatial analysis using unsharp masking and the mad-max filter, a form of second derivative spatial filter, reveals subarcsecond dark and bright loops. Using computed line-of-sight path integrals though the corona based upon our measured radial decrease of electron density, we are able to estimate that the maximum electron density depletion and enhancement in the dark and bright loops respectively is about 12\%. The dark loops can be explained simply by a corresponding gas pressure decrease of 12\% in the presence of a magnetic field, and the bright loops by a temperature decrease of 12\%-24\% compared to the surrounding corona.